Masao Yoshida, a nuclear engineer who took charge of the Fukushima Daiichi power plant two years ago as multiple reactors spiraled out of control after a tsunami, but who ultimately failed to prevent the world’s worst nuclear disaster since Chernobyl, died here on Tuesday. He was 58. The cause was cancer, said the Fukushima plant’s operator, Tokyo Electric Power.

Mr. Yoshida had been chief manager at Fukushima Daiichi for just nine months when a 42-foot tsunami inundated the site on March 11, 2011, knocking out vital cooling systems to the plant’s six reactors. Eventually hydrogen explosions and fuel meltdowns occurred at three reactors, releasing vast amounts of radioactive matter into the environment.

Although the company was widely criticized for its handling of the disaster, which forced more than 100,000 people from their homes, Mr. Yoshida won praise for his effort to minimize the damage. He has been faulted, however, for failing to invest in adequate tsunami walls at the company’s nuclear power plants when he was head of nuclear facilities. Mr. Yoshida later apologized to reporters, saying he had been “too lax” in his assumptions of how big a tsunami might hit the coastal plant.